Telephone system



A June 30, 1925. y 1,543,671

MARGIN/1L /m/en of:

Ecilwarc' Hinrichsen.

by www Aw# Patented .lune 30, 1925.

UNITED STATES lP'ArlsN'r OFFICE.

. EDWARD E. HINRICHSEN, 0F NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION or NEW YORK.

TELEPHONE SYSTEM.

Application led April 23, 19201 Serial NO. 375,886.

To all whom it may concern: Be it known that I, EDWARD E. HINRICH- SEN, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise',-and exact description.

This invention relates to improvements vin signaling systems and has particular reference to a ringing circuit for telephone systems.

In systems wherein ringing transformers are employed in the ringing circuits, the range of applied battery potential is sometimes so greatthat if a transformer is de signed to give a satisfactory alternating current when the battery potential is within a desirable range, the lalternating current potential induced in the secondary or output side of the transformer will become objectionable for proper operating purposes if the battery potential should increase beyond said desirable range.

An object of the present invention is to prevent any undesirable increase in alternat- 1ng current potenial in the `secondary or output side of a ringing transformer.

In accordance with the above object, use is preferably made of a resistance element introduced into the primary of the ringing transformer and normally shunted through p a contact of a marginal relay which opcrates only when the battery potential is n with the primar in excess of the desired ran e. When this occurs, said resistance isf inc udedin series of the transformer and acts to preventt e current in said primary from increasing in proportion to the increase in the applied orw battery potential. The drawing illustrates diagrammatically a preferred embodiment of the invention showing its application to a manual ringin circuit i ore specilicially, the drawing shows Aa telephone line terminating in a subscribers substation '1 of any well known type including the ringer 2. An operators ringrovided which, when actuated, connects t e ringing circuit, including the' secondary or output side of the' ringing transformer 4, to the telephone line to operate the rin' er 2 in the usual manner. Closure of the ower alternate convoltage corresponding to the maximum safe alternating voltage, or, in other words, will only operate when the battery potential is in excess of the range desired for operating purposes. Energization of relay 5 also `establishesa circuit for the ringing inter` rupter or vibrator 8, of any construction known in the art, said circuit extending from battery 6 through the winding of vibrator 8, the contact 9, and the contact of .relay 5 to ground. Vibrator 8 operates and thereby interrupts its own circuit atthe contact 9 which causes the same to release whereupon the energizing circuit is again established. Upon each closure of the valternate contact y10, when vibrator '8 operates, current flows from battery 6 yto the middle point of the primary ofthe transformer 4 through the contact of relay 7 thus'shunting the ballast resistance element 11 which may be a tungsten lamp or other device of similar characteristics. The temu perature-resistance characteristicv of the element 11, is identical with Fig. 3 shown on age 8', section 4; of the third edition of the. Standard Handbook for Electrical Engineers. From said middle int the currenty flows through the left coil of said primary winding, the contact 10 and the co-ntact of relay 5 to ground. Upon each closure of the normal contact 12, the current from battery 6 flows similarl to the middle point of the primary win ing of transformer 4 and from thence through the right coil of said winding, the contact 12 and contactof relay 5 to ground. In this manprimary of the transformer, whereupon the resistance of said element increases as the current through it increases in the manner shown in the Standard Handbook before referred to. It will thus be apparent that when tliefelement l1 is included in the circuit, the current flowing through the primary will be prevented from increasing in proportion to the increase in the applied Y c sistance element, and means connected in bridge of said source for effectively including said reslstance element in series with said source and the primary circuit of saidY transformer when the voltage of said source is increased beyond a certain predetermined value.

2. The combination of a circuit including a transformer, a source of battery supply for said transformer, means for periodically interrupting said battery supply, a normally shunted vresistance element associated with said transformer, and means bridged across 'said source for removing the shunt from said resistance element when the voltage of said source is increased beyond a certain predetermined value.

3. The combination of a. circuit including a transformer, a source of battery supply for said transformer, means for periodically interrupting said battery supply, a normally shunted resistance element in series with the primary of said transformer, and means bridged across' said'source for removing the shunt from said resistance element.

4. The combination of a 'circuit including a transformer, a source of battery supply for said transformer, means for periodically interrupting said lbattery supply, a resist-- ance element and a marginal relay bridged across said Source for effectively including said resistance element in the cuit of said transformer. c

In witness whereof, I hereunto subscribe my name this 21stday of April `A D., 1920.

EDWARD E.HINRICHSEN.

primary cir- 

